/*
 * Copyright 2002-2019 Intel Corporation.
 * 
 * This software is provided to you as Sample Source Code as defined in the accompanying
 * End User License Agreement for the Intel(R) Software Development Products ("Agreement")
 * section 1.L.
 * 
 * This software and the related documents are provided as is, with no express or implied
 * warranties, other than those that are expressly stated in the License.
 */

// features.h does not exist on macOS*
#ifdef TARGET_LINUX
// features initializes the system's state, including the state of __USE_GNU
#include <features.h>
#endif

// If __USE_GNU is defined, we don't need to do anything.
// If we defined it ourselves, we need to undefine it later.
#ifndef __USE_GNU
    #define __USE_GNU
    #define APP_UNDEF_USE_GNU
#endif

#include <sys/ucontext.h>

// If we defined __USE_GNU ourselves, we need to undefine it here.
#ifdef APP_UNDEF_USE_GNU
    #undef __USE_GNU
    #undef APP_UNDEF_USE_GNU
#endif

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <assert.h>
#include <setjmp.h>

int p_safe_exit;

void install_signal_handler(void);
void signal_handler(int, siginfo_t *, void *);
void generate_hlt_segv(int val);

void install_signal_handler() {
  int ret_val;
  struct sigaction s_sigaction;
  struct sigaction *p_sigaction = &s_sigaction;

  /* Register the signal hander using the siginfo interface*/
  p_sigaction->sa_sigaction = signal_handler;
  p_sigaction->sa_flags = SA_SIGINFO;

  /* Don't mask any other signals */
  sigemptyset(&p_sigaction->sa_mask);

  ret_val = sigaction(SIGSEGV, p_sigaction, NULL);
  if(ret_val) {
    perror("ERROR, sigaction failed");
    exit(1);
  }
}

void generate_hlt_segv(int val) {
  int *p = 0;

  p_safe_exit = (int)&&safe_exit;

  printf("EIP of segfault: 0x%x (only accurate with if compiled with -O)\n", (int)&&hlt_segfault);

 hlt_segfault:
  __asm__ __volatile__ ("hlt");


  printf("ERROR!\n");

 safe_exit:
  printf("EIP of safe exit: 0x%x\n", p_safe_exit);
}

void signal_handler(int signum, siginfo_t *siginfo, void *_uctxt) {
  int ret_val;
  ucontext_t *uctxt = (ucontext_t *)_uctxt;
  ucontext_t signal_ctxt;

#if defined(TARGET_MAC)
  printf("signal %d (captured EIP: 0x%x)\n", signum,
         uctxt->uc_mcontext->__ss.__eip);

  uctxt->uc_mcontext->__ss.__eip = p_safe_exit;
#else
  printf("signal %d (captured EIP: 0x%x)\n", signum,
         uctxt->uc_mcontext.gregs[REG_EIP]);

  uctxt->uc_mcontext.gregs[REG_EIP] = p_safe_exit;
#endif
}

int main(int argc, char **argv) {
  install_signal_handler();

  generate_hlt_segv(1);
  return 0;
}
